How in datatables, using server side processing, to make a selection from two tables at once.?

Question

PHP

I am using datatables js script.
There is a table "Orders" with fields 1. Customer 2. Price 3. Order type
But the value of the customer field is the customer's ID in the "Customers" table, and in the frontend I need to display the name of this customer. If I made the table myself, I know how I would make the query, but with datatables I can’t figure out how to do it.
I use an example from the site datatables "Server-side processing" , where there is a selection from the mysql database. There, a selection is configured from only one table. How can I modify this example to suit my needs.